Which of the statements below does not describe antigens? a. The parts of antigen molecules that initiate immune responses are c
alled epitopes or antigenic determinants. b. Antigens can include proteins, nucleic acids, lipoproteins, glycoproteins, and certain large polysaccharides. c. Antigens exhibit immunogenicity and reactivity. d. Antigens only come from microbes.
Antigens are substances which elicits a response by the antibodies. Antigens Antigens include proteins, nucleic acids, lipoproteins, glycoproteins, and certain large polysaccharides.
They parts of antigen molecules that initiate immune responses are called epitopes or antigenic determinants.
The correct answer is d. Antigens only come from microbes. This statement does not describe antigens.
Explanation:
Our immune system produces antibodies when it detects harmful elements, called antigens. Antigens are substances (usually proteins), when introduced into an organism, trigger a defensive reaction. Thus, epitopes are the parts of a molecule that will be recognized by an antibody and to which it will bind. The vast majority of immunogens are proteins. These can be pure proteins or either glycoproteins or lipoproteins. Proteins are generally very good immunogens. Pure polysaccharides and lipopolysaccharides are good immunogens. Nucleic acids are generally weak immunogens. However, they can become immunogenic when they are formed by a single chain or when they are coupled to proteins. In general, lipids are not immunogenic but can behave like haptens. Antigens exhibit (or can show) a series of immunological properties including immunogenicity, which is the ability to stimulate an immune response, that is, to produce antibodies or a state of cellular immunity.
